Domain Name Checker

Hi everyone,

I am not sure if it is the place to post this thread but i was wondering if anybody could help me finding a good domain name checker. I’ve got one but some “whois server name” does not work such as .co.za .de .co.uk .org .net .eu etc…

I have checked the ajax one (link below) but i cant get other domain extension to work.
http://www.ajaxdomainsearch.com/
Please does anybody knows a place or some tutorials that can help me.

Thanks a lot.

Regards,

jerome